The proposed work will deal with the following problems: 1. What is the physiological significance of the Ca2ion - Mg2 ion - activation of adrenal cortex mitochondrial malic dehydrogenase? 2. How does c-AMP serve to maintain the normal structures and functions of the adrenal cortex (prevent atrophy)? 3. What are the factors involved in ACTH-stimulation of steroidogenesis and and how do these factors interact?